Aromatic Chemistry - Benzene Nomenclature (A-Level Chemistry)
Benzene Nomenclature
Aromatic Compounds
Naming Aromatic Compounds
Compounds which contain a benzene ring are collectively known to as aromatic compounds or arenes.
Arenes can be named in two ways:
- As substituted benzene rings – For example, chlorobenzne, benzoic acid (or benzene-carboxylic acid), and 1,3-dimethylbenzene
- As compounds with a phenyl group – For example, phenol or phenylamine. The phenyl group has molecular formula CāHā .
When a benzene ring has more than one functional groups substituted into it, the name of the resulting arene has to include the number of the C atom each functional group is attached to. When numbering C atoms in the benzene ring the following rules are followed:
- If all functional groups are the same – Pick any of the functional groups and give number the carbon atom it is attached to as C number 1. Then count around so that you get the lowest possible numbers.
- If the functional groups are different – Start from the functional group which gives the compound its suffix. Then count around so that you get the lowest possible numbers.
Worked example: Name the following aromatic compounds
Answer:
A. 3-nitro-4-ethyl-phenol
B. 3,5-dichlorophenylamine
C. methyl 3-nitrobenzoate
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